This application is based upon French Patent Application No. 01.10517, filed Aug. 3, 2001, the disclosure of which is hereby incorporated by reference thereto in its entirety, and the priority of which is hereby claimed under 35 U.S.C. xc2xa7119.
1. Field of the Invention
The invention relates to a device for measuring the running parameters of a bicycle. The invention also relates to a bicycle equipped with this device.
In particular, the invention relates to a device for measuring the rotating speed of a wheel and/or the pedaling rate.
2. Description of Background and Relevant Information
In order to measure the rotating speed of a member such as a wheel or a pedal crank, one generally uses as a sensor a Reed relay mounted on the frame and activated by a magnet attached to the movable member.
French Patent Publication No. 2 794 715 calls for this type of device for measuring the pedaling rate. The magnet is mounted on the pedal axis and activates a Reed relay attached to the frame.
European Patent Application No. 402 620, and corresponding U.S. Pat. No. 5,170,161, relate to this type of device that measures the rotating speed of the wheel. This device further has the characteristic of having a wireless connection between the processing unit that is controlled by the Reed relay and the display unit that is located on the handlebar. The sensor and the processing unit are mounted on one of the stays of the fork, the magnet is attached to a wheel spoke, and the display unit is installed on the steering handlebars.
In this case, the sensor is mounted on the bicycle frame and it is a passive element, in this case a magnet, that is attached to the moving member. In addition, for this wireless device, it is the passing of the magnet in front of the Reed bulb, or reed switch, which activates the processing unit transmitter. One measures the rotating speed by measuring the time elapsed between two successive transmitter transmissions. In other words, the transmitter is activated at each turn of the wheel, at each turn it transmits in the direction of the receiver and at each turn the processing unit receiver recalculates the speed. For a bicycle traveling at 36 km/hr, the wheel does about five turns per second. This means that the transmitter transmits to the receiver and the speed is recalculated five times in one second.
For each transmission the transmitter draws energy from the battery.
These wireless devices are easy to install precisely because of the wireless connection between the transmitter and the receiver. Nevertheless, these devices call for a measurement refresh rate that exceeds what is actually necessary, and there is a substantial consumption of energy by the transmitter.
Another drawback to these devices is that the position of the magnet with respect to the Reed bulb has to be adjusted so that the magnet passes properly in front of the bulb at the right distance. Frequently, when the wheel is dismounted or when the bicycle is transported, the magnet moves accidentally. In this case, it needs re-adjusting.
Furthermore, transmission between the transmitter and the receiver generally occurs by means of directional antennas in order to decrease the transmission power required, as well as interfering transmissions. To ensure proper functioning, these antennas need to be oriented precisely with respect to one another, such that it has never been envisioned until now to mount the transmitter and the receiver differently than to have both of them attached to the bicycle frame so that they are immovably or almost immovably fixed with respect to one another.
One object of the invention is to propose a wireless measuring device having a reduced power consumption with respect to the prior art devices.
Another object of the invention is to propose a measuring device that is simpler to install on the bicycle.
Other objects and advantages of the invention will become apparent through the description that follows.
The device for measuring the running parameters of a bicycle include:
a sensor capable of reacting to a revolution of a rotationally movable member through a change of state and operating along a cycle of changes of state, the sensor being provided to be mounted on a rotatable member of the bicycle;
a transmission circuit having an antenna;
a reception circuit having an antenna.
The transmission circuit has a circuit for calculating a value of the running parameter based on the signal originating from the sensor, a transmitter connected to the antenna to transmit this value to the receiving device, and an optimization circuit for activating the transmission of the transmitter at moments independent of the changes of state of the sensor, or independent of the periodicity of the chances of state of the sensor.
The bicycle is equipped with the device in question having a transmission circuit mounted on a portion of the bottom bracket/crank gear and/or one of the two wheels that is rotationally movable.